Ultra high frequency receiving system



Sept. 2, 1941. w. s. HALSTEAD ULTRA HIGH FREQUE NCY RECEIVING SYSTEM Filed Sept. 1 1958 s Sheets-Sheet 1 0km 004 5 r AIVTZNWA M T m m #80 w/Lefiaw c5. M126 By I Q ATTORNEY jrsgz' Se t. 2, 1941. w. s. HALSTEAD 2,254,213

ULTRA HIGH FREQUENCY RECEIVING SYSTEMv Filed Sept. 1, 1938 3 Sheets-Sheet 3 I I 23 TIME'DIZA) IN VEN TOR.

mew, Q9 mm ATTORNEYG.

Patented Sept. 2, 1941 ULTRA HIGH FREQUENCY RECEIVING SYSTEM William S. Halstead, Huntington, N. Y., assignor of one-third to John Brady, Washington,

Application September 1, 19st, Serial No. 228,052

3 Claims.

This application is a continuation-in-part of my copending application Serial No. 42,703, filed September 28, 1935, for Radio traffic control system, now Patent No. 2,131,042, granted September 27, 1938.

My invention relates in general to'directional ultra high frequency vehicle communications systems, and is more particularly concerned with means for receiving polarized ultra high frequency radio waves directed along a lane of traffic for vehicle control purposes.

It is a primary object of this invention to provide directionally-selective means for receiving ultra high frequency radio wave energy in a vehicle, said wave energy being transmitted along the lane of traific on which said vehicle is proceeding by a directional ultra high frequency transmitter of the type shown in my copending application, supra, of which this is a continuation-in-part.

It is a further object of my invention to provide directionally-selective ultra high frequency receiving means which may readily be installed on vehicles for the purpose of efiecting control of traffic signal indicators mounted within said vehicles.

It is an additional object of my invention to provide means for effecting connection of an ultra high frequency receiver with a second receiver designed for operation on lower frequencies, said connection effecting utilization of said second receiver for both ultra high and lo frequency radio signals.

Other and further objects of my invention reside in the constructional and circuit arrangements for selecting a particular-plane of polarization of a directional space-transmitted radio wave and for automatically effecting discrimination between ultra high frequency wave energy directed along different lanes of traffic as set forth in the specification hereinafter following and by reference to the accompanying drawings in which:

Figure 1 is a front elevational view of the instrument panel and windshield of a vehicle to illustrate a preferred disposition of a horizontal dipole antenna and ultra high frequency detector employed in the receiving system;

Fig. 2 is a side elevation of the same vehicle showing the horizontal dipole and detector unit illustrated in Fig. 1;

Fig. 3 is a circuit diagram of one form of ultra high frequency detector, amplifier and associated trafiic signal indicating means employed in a vehicle to give audible and visual indication of the character of an external traffic control signal;

Fig. 4 is a schematic block diagram showing connections between an ultra high frequency detector unit and a conventional low frequency broadcast receiver, the output circuit. of the receiver being provided with visual means for indicating the character of the external traflic control signal;

Fig. 5 is a circuit diagram of a preferred form of connection between an ultra high frequency detector unit and a low frequency broadcast receiver, showing means employed for selectively operating traffic signal indicating lamps installed within a vehicle and connections whereby automatic means are provided for removing a coupling connection between the ultra high frequency receiver and the audio amplifier of the broadcast receiver when a radio traific signal is being received by the ultra high frequency detector;

Fig. 6 is a circuit diagram of a modification of the signal lamp and the relaycircuit of Fig. 5

, showing the addition of chime signals to the indicator system;

Fig. 7 is an elevational view of a portion of the interior of a locomotive cab equipped with anultra high frequency receiver and a dipole antenna having means for rotating it through signal; and

Fig. 9 is a circuit diagram of an ultra high frequency receiver and associated electric wave filters of the electro-magnetic type for effecting selective operation of signal lights installed in the locomotive cab.

Referring' to the drawings in detail, wherein like reference characters indicate corresponding parts throughout the several views, each form of the invention illustrated herewith embodies quasioptical radio wave receiving means such as provided by an ultra high frequency detector 30, Fig. 1, combined with a directionally selective antenna such as a horizontal dipole 66 to effect reception of radio traffic control signals from a directional transmitter of the type shown in my copending application, supra, of which this is a continuation-inpart.

In the particular embodiment of the invention shown in Fig. 1 in which the ultra high frequency receiver is installed on a. vehicle, a horizontal dipole antenna 65 is mounted on the outside of the vehicle at a point Just above the windshield I 02 which location has a distinct advantage in that the dipole is substantially in line of sight relationship to the transmitting dipole, regardless of the presence of other vehicles of moderate height on the traffic lane ahead. As pointed out heretofore, metallic structures reflect ultra high frequency radiant energy and act as a shield through which the wave energy does not effectively penetrate. It is desirable therefore to mount the receiving dipole at such a height that the presence of the steel body of a preceding vehicle, will not prevent the reception of the radio trafllc control signal. Moreover, the location as described has an additional advantage in that the shielding effect of the body proper reduces signal pick-up from an ultra high frequency transmitter which has been passed. The detector housing 81, Fig. 1, shown in the drawings with its front cover removed, may be installed either on the interior or exterior of the vehicle at a point substantially adjacent to the mid-point of the dipole as indicated so that short leads between the dipole and'the input circuit of the detector are eifected. High frequency choke coils 3| and 32, Fig. 3, in the anode and rid leads of the detector circuit are also included in the housing of detector unit 61. The output circuit of detector tube 30 and the power supply leads are placed in a shielded cable, indicated by dotted lines in Fig. 1. The cable makes connections with the input and power supply terminals of an amplier I5. Visual signal indicating devices such as a red lamp I04 and a green lamp I05, connected to suitable frequency discriminating devices such as electric wave filters, not shown in Fig. 1 but described and illustrated hereinafter, are located in proximity to the instrument.

panel of the vehicle. The lights are installed on or near the instrument panel in the drivers line of vision. A loud speaker 68 is disposed behind the instrument panel or in any other effective location to provide audible indication of the character of the tramc signal as described in my copending application, supra.

A circuit diagram of one-form of ultra high frequency receiver with visual and audible signal indicators is shown in Fig. 3. The parallel rod plate and grid leads of detector tube 30 are connected to the ends of dipole 66 as shown, or by inductive coupling .as illustrated in Fig. 9. A variable condenser, shown in dotted lines may be used if aperiodic tuning is not desired. Radio frequency chokes 3| and 32 are inserted in series in grid and plate leads. Resistor 33 is connected in series with the grid lead as illustrated, one side of this resistor being groundedin conventional manner. The cathode of the detector tube is grounded and a small by-pass condenser 34 is connected between the plate circuit and ground. The plate circuit is completed through the primary winding of coupling transformer 35 which is connected to a source of plate poten I08 having a plurality of windings to which are connected a loud speaker 68 and several frequency discriminating devices such as electric wave filters or tuned amplifiers I09 and III]. The output circuits of the filters or tuned amplifiers are connected to visual signal indicators, such as neon lamps I04 and I05, or relay-controlled lamps such as shown in Figs. 5, 6 and 9. Each filter or tuned amplifier is tuned to pass wave energy having a predetermined frequency -which is correlated with definite traflic control functions as described in my copending application, supra. Thus the red light I04 will be controlled only by wave energy of frequency FI and the green light I05 will be energized only when the ultra high frequency carrier is modulated by wave energy of frequency F2. Both signals will be heard on the loud speaker, 68. Although apparatus is shown for use with control waves of audio frequency nature, it is obvious that the ultra high frequency carrier can be modulated by a plurality of control signals of the radio frequency type if desired. In this event modulating control frequencies above 10,000 kilocycles may be employed together with amplifying and frequency discriminating equipment designed for use with radio frequency rather than audio wave energy.

A modification of the ultra high frequency receiving and signal indicating system is shown in the schematic diagram of Fig. 4 in which the output circuit of the ultra high frequencydetector 61 is coupled to the audio frequency circuit of a conventional form of broadcast receiver III in such manner that the loud speaker of the broadcast receiver may be employed in making audible the demodulated ultra high frequency signals. Since the signal delivered to the broadcast amplifier by the ultra high frequency receiver will be heard from loud speaker 88 regardless of the broadcasting wavelength to which the radio frequency circuits of the broadcast receiver may be tuned, such as a receiver will, without tuning adjustments on'the part of the driver provide both the customary programs from broadcasting stations and occasional highway traflic instructions, warnings and radio trafflc control signals from directional ultra high frequency roadside transmitters of the type described in my Patent No. 2,131,042, supra. As each section of the composite receiver has its own volume control adjustment, the signal level of either type of communication can be controlled independently of the other. 'By connecting the input circuits of suitable frequency discriminating devices, such as sharply tuned electric wave filters or amplifiers I09 and H0, to the output of the broadcast receiver, as shown in dotted lines, selectively operated visual signal indicators such as neon lamps I04 and I05, may be visibly actuated by the output voltage of filters I09 and H0 when a sustained control signal is received to give indication of the character of the traffic lights ahead of the car.

In the preferred form of connection between the receivers shown in Fig. 5, the output circuit of ultra high frequency detector 81 is connected through a shielded cable to the primary winding of a coupling transformer I55. The secondary winding of the transformer is connected in conventional manner as shown, to a volume controlling potentiometer I56 whose arm is conaeagms 3 which is connected to the plate voltage supply lead of the broadcast amplifier. Signal voltage coupling means between the plate circuit of tube I51 and the input circuit of the power amplifier tube I59 of the broadcast receiver is provided by coupling condenser I60, inserted in lead I6I which is connected to the grid circuit of the power amplifier through switch I62 as shown. Signal voltage from the ultra high frequency detector is also supplied to the input circuits of two tuned amplifiers I63 and I64 by connection with the primary winding of coupling transformer I55 as illustrated. The output circuit of amplifier I63, which is tuned to pass sustained wave energy of frequency Fl correlated with the traffic control stop signal, is connected to the tuned winding I65 of a relay'as shown. The armature I66 of the relay is connected with a source of E. M. F. such as car battery I61. The fixed contract I68 of the relay is connected to one side of the filament of an electric lamp I69, the other side. being connected to the storage battery as illustrated. Any conventional pilot light color disc or lens, not shown, may be placed in front of lamp I69 to give itthe red stop signaling characteristic. The red light can be energized only when sustained wave energy of frequency PI is received since wave energy having other frequencies will shown. The armature I1I, is connected to the storage battery, and the'fixed contact I12 is connected to one side of the filament of green lamp I13 so as to energize the filament when the armature is moved to the contact. Both relays are preferably of the slow-response type to effect control of the lights only when sustained control signals are received. Speechv or other modulating signals will not effect their operation because of the lack of a long-sustained tone of a particular frequency. However, speech or other modulated wave energy will be applied to the control grid of power amplifier I59 of the broadcast receiver and will operate loud speaker I14.

In the arrangement of Fig. 5 thus far described,'it is obvious that the light-control signals of frequency FI and F2 will be heard from loud speaker I14. Since this may not be desirable under many corcumstances, automatic means is provided by which the signal coupling circuit between the ultra high frequency and broadcast receivers is disconnected as long as the sustained light control signals are being received. Thus if a bnoadcast program is being received, the signal lights may be operated in the car without interference from the sustained control signals, This functionis efiected by the provision of an additional contact arm I15 on the armature I66, and a similar additional arm I16 on armature I1I. Fixed contact I11 is normally in position against arm I15, and contact I19 is normally touching arm I16. The contacts and arms of the two relays are in series connection as shown so that if either relay is operated, the auxiliary circuit will be broken. The auxiliary circuit is connected across switch I62 as shown so as to close or open the coupling circuit between the ultra high frequency and broadcast receivers. Normally, when no sustained control signal is received'the relays are in the inoperative position with the auxiliary contact arms closing the circuit between the ultra high frequency and broadcast receivers. Thus speech modulated highway instructions and warnings from roadwis'e ultra high frequency transmitters (not shown) may be made audible to the driver Z by loud speaker I14. As soon as the sustained control signal of'frequency FI or F2 is received either one of the relays will close and the control signal will be cut from the broadcast circuit. Since the relays are of the slow acting type, the control tone will be heard for a moment before the selected relay operates, thus giving the driver a brief aural indication of the character of the signal as previously described in my Patent No. 2,131,042, supra. Fig. 6 shows an automatic disconnecting arrangement similar to that in Fig. 5 with the addition of small single-stroke chimes I19 and I00 connected to the red and green light circuits respectively, the chimes being employed to give aural traflic signal warnings where the sound of the control signals from the loud speaker is not effective.

A preferred arrangement of ultra high frequency receiving apparatus suitable for use in connection with the transmitting system of Figs. 25 to 28 of my copending application Serial No. 42,703 now Patent No. 2,131,042, granted September 27, 1938, is illustrated in Figs. 7 to 9 inclusive. The adjustable receiving dipole, shown in horizontal position at I35, Fig. 'l, is connected to an ultra high frequency detector unit I36, both units I35 and I36 being installed near the top and at the front of the cab of a locomotive as indicated. The demodulated output of detector unit I36 is supplied, as schematically shown in Fig. 30, to the input circuit of an amplifier I31. The output of amplifier I31 is connected to a loud speaker I38, as shown, and to the input circuits of electrical wave filters I39, I40 and I5I, preferably of the tuned reed type, each tuned to a predetermined signal control frequency as FI, F2 and F3, respectively. The output circuits of the filters I39, I40 and I4I, are connected to signal lights I42, I43 and I44, respectively, installed in proximity to the instrument board of the locomotive. Means are thus provided by which a plurality of control signals each having a different pre determined frequency value, such as FI, F2, F3, as well-as telephonic signals emitted by an ultra high frequency transmitter may be received in the cab of the locomotive by ultra high frequency detector I36 and thereafter separated by suitable filter devices into the constituent modulating control signals of frequency FI, F2 and F3 to effect selective visual energization 'of signal lights of different colors as well as audible reception of the traffic control and speech signals.

A circuit diagram of such an ultra high frequency receiving and signal indicating system is shown in Fig. 9 in which the output circuit of ultra high frequency detector unit I 36, similar to that of Fig. 3, is connected to the primary windings of amplifying transformer 36 disposed in series in the positive plate battery lead. The secondary windings of transformer 35 are connected in well known manner to the input circuit of amplifier I91 whose output is connected to loud speaker I36 and the exciting coils of tuned reed filters I39, I49 and MI. The output coils of filters I39, I40 and I are connected to the input circuits of amplifiers I46, I41 and I48, respectively, whose respective output circuits are connected to thewindings of relays I49, I 60 and III respectively as shown. The armature contacts of relays I49, I50 and II are connected in series with electric lamps I42, I43 and I44 respectively, and a source of electric potential such as a storage battery I52, as shown.

It is obvious that a time delay relay 28, and

a power and brake control relay 29, may be added if desired to the circuit of red lamp I42 so as to bring the train to a stop should the brakes not be applied within a predetermined time after the stop signal has been energized.

The operation of the circuit shown in Fig. 31, is such that when an incoming modulating signal, having a control frequency Fl, for example, is supplied to amplifier I31, the amplified signal is delivered to the exciting coils of tuned reed filters I39, I40 and I. The metallic reed of filter I39 which is tuned to respond to predetermined signaling frequency PI, is forced into sustained vibration by the signal voltage in the exciting coils having frequency FI and a small voltage is thereby induced .in the output coils of the filter unit in well known manner. The filtered output voltage is then supplied to the input circuit of amplifier I46 whose output voltage causes theactuation of relay I49 and the subsequent closing of the lighting circuit of red lamp I42 as may be understood readily from the circuit diagram. Since the tuned reeds of filters I40 and HI are not forced into vibration by the applied signal voltage of frequency FI no voltage is induced in the output coils of these filters,

and consequently no actuating current is supplied to relays I50 and III controlling the operation of lamps I43 and I44 respectively. It is further pointed out that a sustained electrical wave of givenfrequency such as PI is necessary to effect sufiicient vibration of the reeds of the filter units to induce an operative voltage in the output coils of the filters. Thus reception of speech modulated signals of constantly varying frequency and amplitude does not interfere with the operation of the visual signal indicating means. Moreover,-as tuned reed filters of the type described are extremely selective with regard to frequency response characteristics they thereby effect the rejection of all but the proper control signals in the output circuits of the filter units.

It will be recognized that the illustrative systems described herein are capable of considerable modification and rearrangement without departing from the spirit and scope of the invention, and it is therefore to be understood that the following claims embrace all'such modifications and equivalent arrangements as may fair- .ly be construed to fall within the scope of the invention.

traffic control signals, means for coupling the output circuit of the second receiver to the input circuit of the audio frequency amplifier associated with said first receiver, and relay-controlled means operated by said tone modulated trafilc control signals received by the second 7 receiver for automatically disconnecting said coupling means from the output circuit of said second receiver, said relay-controlled means being non-responsive to said voice modulated traffic control signals which are reproduced in said loud speaker.-

2. A radio receiving system for vehicles comprising. in combination, a radio receiver tunable to one radio communications band, a second receiver tunable to another radio communications band for receiving voice modulated and tone modulated traiilc control signals, tone frequency discriminating means connected to an output circuit of said second receiver, a relay controlled by tone signal energy of predetermined frequency passed by said frequency discriminating means, a signal coupling connection between an output circuit of said second receiver and an input circuit of said first receiver, said coupling connection being removable by the selective operation of said relay as determined by received tone signal energy of predetermined frequency, said relay being inoperative by said voice modulated signals which are reproduced in said loud speaker.

3. A radio receiving system for vehicles comprising, in combination, a non-directional antenna mounted on a vehicle, a radio broadcast receiver tunable to one radio communications frequency band coupled with said antenna and including an audio frequency amplifier and a loud speaker operated by saidamplifier, a directionally selective antenna mounted on the vehicle for receiving voice modulated and different tone modulated trafllc control signals propagated towards said vehicle, a radio trafllc control receiver operative in another radio communications frequency band coupled with said directionally selective antenna, means for coupling the output of said radio traflic control receiver to the input' circuit of the audio frequency amplifier associated with the first said broadcast receiver, elec- What I claim as new and desire to secure by Letters Patent of the United States is as fol-' lows:

l. A radio receiving system for vehicles com-' tric' wave selectively responsive means and indicating means connected to said traflic control receiver and operative in accordance with a particular tone modulated trafilc control signal received by said trafilc control receiver, each of said tone modulated traflic control signals being correlated with trafllc conditions for vehicle traffic control purposes, and relay switch means operated by said selectively responsive means for automatically disconnecting said coupling means from the output circuit of said tramc control receiver whereby said tone modulated signals are not reproduced by said loud speaker, said relay switch means being inoperative by said voice modulated signals whereby said voice modulated traffic control signals are reproduced in said loud speaker.

WILLIAM S. HALSTEAD. 

